"How do I make it taxable on the tax return,"

Is it not showing as taxable?

For an entry question, here's the Help article:

https://accountants.intuit.com/support/en-us/help-article/form-1099-r/entering-form-1099-r-proseries...

If you are questioning the G for the conversion, here is the IRS guidance:

https://www.irs.gov/pub/irs-pdf/i1099r.pdf

"For a direct rollover of a distribution from a section 401(k) plan, a section 403(b) plan, or a governmental section 457(b) plan to a designated Roth account in the same plan, enter the amount rolled over in box 1, the taxable amount in box 2a, and any basis recovery amount in box 5. Use Code G in
box 7."